Rapid scanning longwave infrared absorption spectroscopy of chemical nerve agent simulant destruction in fireballs

Chemical warfare using highly toxic organophosphorus nerve agents poses an extreme threat to national security, in part because chemical weapons of mass destruction are more readily attainable than nuclear weaponry. Study of the destruction of such compounds is necessary to developing effective countermeasures, and destruction by exposure to combusting fireballs is a chief area of interest. Absorption spectroscopy targeted at the longwave infrared “fingerprint” region is a common technique used in the measurement of nerve agent and simulant materials due to the wealth of information that can be obtained from measurements taken over a wide spectral range. Difficulties arise in the area of fireball destruction as these events tend to destroy the substances on the order of 10-3 to 10-2 seconds, too quickly for traditional longwave Fourier Transform Infrared spectroscopy systems, limited to a few hundred hertz, to monitor. In this research, a new diagnostic system was designed, constructed, and validated which allowed for kilohertz speed measurement of the longwave infrared region. The system, a dispersive scanning spectrometer using a rapidly rotating grating, was inspired by the work of Pimentel and other researchers from the 1960s. In addition to a 1.2 kHz average repetition rate, the scanning spectrometer is capable of scanning the infrared region of 850cm-1 to 1350cm-1 with a spectral resolution better than 10cm-1. This developed system was used to collect a robust set of benchmark data for the validation of computational models of the destruction of the nerve agent simulant Diisopropyl Methylphosphonate (DIMP) inside fireballs. An experimental apparatus and test procedures were developed to facilitate the measurement of DIMP destruction in constant volume fuel and oxidizer “closed bombs.” Data were obtained for four distinct closed bomb conditions, and supplemental data were obtained from a series of six tests using small scale explosive charge detonations. Collected data has been analyzed to ensure its quality as a robust set of benchmark data. Experimental repeatability and measurement variability across multiple repeat tests is discussed, and time resolved absorption spectra are investigated for indicators of potential decomposition products.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Butler, Austin Josiah

Contributors dc:contributor

• Glumac, Nick G
• Krier, Herman
• Lee, Tonghun
• Elliott, Gregory

• Spectroscopy
• Fireballs
• Longwave Infrared

Statement dc:rights

• Copyright 2022 Austin Josiah Butler

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/117733

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F117733